EP3003988B1 - System for treating fluids by producing corona discharges in a fluid volume - Google Patents

Description

The invention relates to a device for the treatment of fluids in the form of drinking water, process water, wastewater or aqueous solutions by generating corona discharges in a fluid volume, the device comprising an electrode assembly having at least one cylindrical cathode and at least one in the interior of the cathode and at a distance from Cathode arranged line-shaped anode and a high voltage unit for generating high voltage pulses, wherein the high voltage unit is connected to the electrode assembly to apply the at least one anode with high voltage pulses, and wherein the electrode assembly for receiving the fluid to be treated in the space between the at least one cathode and the at least one anode is set up. A number of dielectric surface elements extend radially from the at least one line-shaped anode in the direction of the associated cylindrical cathode.

For cleaning, disinfection and / or decontamination of fluids, especially drinking water, service water and wastewater is known to use a plasma treatment. In this case, the plasma can not only be generated in a gaseous phase outside the fluid volume and then introduced into the fluid volume with the gas. Rather, plasma can be generated for fluid treatment in the fluid volume itself by generating corona discharges.

MA Malik, Y. Minamitani, S. Xiao, JF Kolb and KH Schoenbach: Streamers in Water Filled Wire-Cylinder and Packed-Bed Reactors, in: IEEE Transactions on Plasma Science, Vol. 2, April 2005, pages 490-491 disclose the generation of corona discharges in a volume of water. High-voltage pulses with pulse durations of 500 nanoseconds (FWHM) with pulse rise times of 80 to 150 nanoseconds and pulse decay times of 400 nanoseconds at a high voltage of up to 90 kilovolts are described here. In the plasma channels, active species such as hydrogen peroxide and hydroxide are generated which, due to their short lifetime, can not sufficiently interact with impurities in the fluid volume to be treated. By filling the fluid volume with silica gel beads (silica gel balls) with a diameter of 3 to 5 mm, a more homogeneous plasma distribution in the reactor volume is achieved.

From MA Malik: Water Purification by Plasmas: Which Reactors are Most Energy Efficient ?, in: Plasma Chem Plasma Process (2010) 30: 21-31 and from MA Malik: Water purification by electrical discharges, in Plasma Sources Science and Technology (2001), Vol. 10, No. 1, 82-91 It is known that the pulse-operated reactors, in which plasma is formed in a gas phase and the fluid solution to be treated is sprayed, are very efficient.

Z. Machala, B. Tarabová, M. Pilach, K. Hensel, M. Jander, E. Špetlíková, P. Lukes: Plasma Agents in Water and Surface Decontamination, in: NATO Advanced Research Workshop, Plasma for Bio-Decontamination, Medicine and Food Security, Jasná, Slovakia, March 15-18, 2011, Ed. Karol Hensel and Zdenko Machala, pages 45-46 describe the bio-decontamination of water and surfaces with high voltage discharges under atmospheric pressure. The water to be treated is sprayed into the cold plasma generated thereby. The contaminated water flows directly through the hollow needle electrode and thus through the plasma-active zone. The cold atmospheric pressure plasma is generated with repeated pulses with a pulse duration in the nanosecond range.

Out WO 97/37938 A1 is known, an oxidizing gaseous plasma outside of the fluid volume and introduce as plasma gas flow in a fluid volume to be treated.

WO 2009/006993 A2 discloses a reactor for high voltage impulse disinfection of bacteria-contaminated fluids with pulsed underwater corona discharge and a method thereof. On the subject to high voltage potential electrode is a ceramic layer. In this case, high-voltage pulses with pulse durations of more than 100 nanoseconds and preferably 200 to 300 nanoseconds pulse duration are used for rise times of the high-voltage pulse below 100 nanoseconds.

US 5,603,893 A discloses a plasma reactor for treating gas streams with sawtooth electrodes applied with pulses of a pulse width of 20 to 100 nanoseconds and short pulse rise times of 10 to 20 nanoseconds.

US 2005/0106085 A1 discloses a reactor for treating a gas stream with plasma.

US 2011/0190565 A1 describes a plasma reactor for converting gas into liquid fuel by means of needle electrodes. In this case, no corona discharge, but a Gleitbogenentladung is used.

US 5,855,855 A discloses an exhaust gas purification reactor by corona discharge in a tubular reaction space.

DE 698 13 856 T2 describes a corona discharge reactor for use in processing gaseous media by means of an electrical discharge having a plurality of individual reactor chambers in which the electrical pulses are applied simultaneously.

Jen-Shih Chang, Phil A. Lawless and Toshiakia Yamamoto: Corona Discharge Processes, in: IEEE Transactions on Plasma Science, Vol. 6, December 1991, pages 1152-1166 describe corona discharge processes in gases, inter alia, in a reactor filled with dielectric pellets for increasing the electric field for exhaust gas purification.

US 2010/0240943 A1 describes a device for reducing organic contaminants of volatile organic compounds in an aqueous environment by means of corona discharge. Short high-voltage pulses with pulse widths of 40 nanoseconds and pulse frequencies up to 1000 hertz at pulse voltages up to 40 kilovolts are proposed.

A. Pokryvailo, M. Wolf, Y. Yankelevich, S. Wald, LR Grabowski, EM van Veldhuizen, WR Rutgers, M. Reiser, B. Glocker, T. Eckhardt, P. Kempenaers and A. Welleman: High-Power Pulsed Corona for Treatment of Pollutants in Heterogenous Media, in: IEEE Transactions on Plasma Science, Vol. 5, October 2006, pages 1731 to 1743 describe the treatment of contaminated gas or water streams with pulsed corona discharge. Pulse durations of 100 nanoseconds at pulse repetition rates of 500 hertz are proposed.

Proceeding from this, it is the object of the present invention to provide an improved device for the treatment of fluids by generating corona discharges in a fluid volume, wherein an electrode arrangement located in the fluid volume is subjected to high-voltage pulses.

The object is achieved by the device with the features of claim 1. Advantageous embodiments are described in the subclaims.

Under a fluid according to the present invention is drinking water,

Industrial water, sewage or other aqueous solution understood.

It is proposed that, starting from the at least one line-shaped anode, a number of dielectric surface elements extend radially in the direction of the associated cathode. Thus, a coaxial, linear anode is arranged in the interior of a cylindrical cathode. From this coaxial linear (wire or rod) anode then extend radially star-shaped dielectric surface elements radially in the direction of the cylindrical cathode surrounding the anode. In this case, these dielectric surface elements span a surface along the longitudinal extension direction of the anode and radially on a path between anode and cathode. With such a radial surface arranged in the space between the anode and cathode dielectric surface elements, the distribution of the corona discharges in the fluid volume and the penetration of the fluid to be treated can be significantly improved.

It is also conceivable that a plurality of dielectric disks are arranged one behind the other in the longitudinal extension direction of a common anode. The anode extends through the dielectric disks. The dielectric disks in turn extend radially in the direction of the associated cathode. The dielectric disks in this case have passage openings for passing the fluid to be treated.

With the aid of these dielectric disks arranged one behind the other, the fluid volume is divided and an improved distribution of the corona discharges in the fluid volume is achieved. In this case, it is advantageous if a (wire / rod) anode extending in a line-shaped manner coaxially with respect to a cylindrical cathode extends in the interior of the cylindrical cathode. This anode is preferably arranged coaxially with the dielectric disks. However, it is also conceivable that a plurality of such line-shaped anodes extend through the dielectric disks arranged one behind the other, wherein these anodes and the dielectric disks are surrounded by a cylindrical cathode which limits the volume of fluid.

The device is based on the use of very short high voltage pulses with pulse durations in the range of 50 to 400 nanoseconds, and in particular very short pulse rise times of the high voltage pulses in the range of 1 to 40 nanoseconds to allow very efficient fluid treatment in almost the entire fluid volume. The very short pulse rise times lead to large shock waves and to a rapid transfer of energy to the electrons and thus to efficient reaction-chemical processes. Due to the very short high voltage pulses with very steep edge, the risk of flashovers is also reduced, i. the transition from extended corona discharges to localized spark discharges. It also ensures that as little energy as possible is used to heat the plasma and the fluid.

Due to the very short pulse rise times in the range of 1 to 40 nanoseconds with pulse durations in the range of 50 to 400 nanoseconds, current pulses in the corona discharge are achieved with very high current peaks and significantly shorter pulse times. With a pulse duration of about 250 nanoseconds (FWHM), for example, current periods of about 100 nanoseconds are achieved, the current pulse being significantly attenuated. The steep rising edges of the short high-voltage pulses thus lead to very short and sharp current pulses with the result that the fluid treatment in the fluid volume is very efficient.

The pulse repetition rate is preferably in the range of 10 to 1000 hertz. The idle time between two consecutive high voltage pulses may in one embodiment be longer than the pulse length of the high voltage pulses. This ensures that the generated plasma has subsided first.

The pulse repetition rate is preferably in the range of 50 to 150 hertz.

The voltage amplitude of the high voltage pulses should be greater than 5 kilovolts and preferably in the range of 50 to 200 kilovolts, and more preferably up to 200 kilovolts. Corona discharges can be realized in this area, the energy of which is essentially converted into chemical and physical reactions that can be used for the treatment of the fluid, without a significant risk of charge breakdowns to the cathode and energy being uselessly transferred into a heating of the fluid. In this area, however, it is also ensured that the resulting current pulses have a sufficient amplitude.

An electrode assembly may have a plurality of anodes, wherein the anodes or groups of anodes are alternately applied to the high voltage pulses. In this way, a large-scale distribution of corona discharges in the fluid volume can be ensured. After applying one high voltage pulse to one anode or group of anodes, the cooldown can be used to apply a high voltage pulse to another anode or other group of anodes without the corona discharge there being generated by the decay phase in the region of the other previously loaded anode or group of anodes is affected. Thus, different spatial areas of the fluid volume can be treated with corona discharges very efficiently in a small time window alternately one behind the other.

Optionally, it is conceivable that the plurality of anodes are simultaneously, i. be acted upon simultaneously with high voltage pulses.

The at least one anode of the electrode arrangement can be arranged to be rotatable about a rotation axis. In this case, a drive unit for rotating the at least one anode about the axis of rotation during the treatment of the fluid intended. In this way, it is possible to best distribute the corona discharges in the fluid volume. The treatment of the fluid is further enhanced by turbulence of the fluid caused by the rotation of the anodes. The rotational frequency of the anodes is preferably in the range of the pulse repetition rate. Just as in the case of alternating application of different anodes, rotation of the at least one anode about an axis of rotation makes it possible to generate corona discharges successively in different regions of the fluid volume, wherein the corona discharges are not impaired by the decay behavior of corona discharges generated immediately before.

The corona discharges are preferably formed on marginal edges and in particular on sharp-edged sections of the anode. By a jagged or sharp-edged surface of the anode with marginal edges can be achieved that as many corona discharges is achieved when exposed to high voltage pulses of the anode.

According to the above-described division of the electrically active anode into a plurality of anodes, it is also conceivable to divide the cathode into a plurality of spatially spaced-apart cathodes, and to control these simultaneously or alternately. It is also conceivable to divide both the anode and the cathode into a plurality of separate anode-cathode pairs.

The at least one anode may be surrounded by at least one perforated tube having openings. The tube may have a gas inlet for supplying reaction gas. The corona discharges generated by the application of high-voltage pulses to the anode thereby break up the gas molecules into active radicals, such as, for example, into atomic oxygen. The corona discharges extend from the anode, starting through the openings into the fluid volume. The filaments of corona discharges interact both with the introduced reaction gas and the surrounding fluid.

Figur 1

- Skizze einer Einrichtung zur Fluidbehandlung mit einer Elektrodenanordnung und einer Hochspannungseinheit;

Figur 2

- Diagramm eines auf die Elektrodenanordnung beaufschlagten Hochspannungspulses mit resultierendem Strompuls;

Figur 3

- Skizze der Einrichtung aus Figur 1 mit bei Beaufschlagung mit Hochspannungspulsen resultierenden Koronaentladungen im Fluidvolumen;

Figur 4

- Skizze einer Einrichtung mit zusätzlicher Gaszufuhr;

Figur 5

- Skizze einer Einrichtung zur Fluidbehandlung mit gelochter Umhüllung der Anode;

Figur 6

- Skizze einer Einrichtung zur Fluidbehandlung mit einer Füllung des Volumens mit Materialien in funktionaler oder katalytischer Oberfläche;

Figur 7

- Skizze einer erfindungsgemäßen Ausführungsform der Einrichtung mit dielektrischen Scheiben;

Figur 8

- Skizze einer erfindungsgemäßen Ausführungsform der Einrichtung mit sich sternförmig radial von der Anode zur Kathode erstreckenden dielektrischen Flächenelementen;

Figur 9

- Skizze einer erfindungsgemäßen Einrichtung mit einer Mehrzahl von nebeneinander angeordneten Elektrodenanordnungen;

Figur 10

- Skizze einer Einrichtung zur Fluidbehandlung mit einer drehbar angeordneten Elektrodenanordnung und einer Antriebseinheit;

Figur 11

- Skizze einer Einrichtung zur Fluidbehandlung mit mehreren alternierend mit Hochspannungspulsen beaufschlagten Anoden;

Figur 12

- Skizze einer Einrichtung zur Fluidbehandlung mit mehreren Gruppen von Anoden, die alternierend mit Hochspannungspulsen beaufschlagt werden.

The invention will be explained in more detail with reference to embodiments with the accompanying drawings. Show it:

FIG. 1

- Sketch of a device for fluid treatment with an electrode assembly and a high voltage unit;

FIG. 2

- Diagram of a voltage applied to the electrode assembly high voltage pulse with a resulting current pulse;

FIG. 3

- sketch of the device FIG. 1 with corona discharges in the fluid volume resulting from the application of high voltage pulses;

FIG. 4

- sketch of a device with additional gas supply;

FIG. 5

- Sketch of a device for fluid treatment with perforated cladding of the anode;

FIG. 6

- Sketch of a device for fluid treatment with a filling of the volume with materials in functional or catalytic surface;

FIG. 7

- Sketch of an embodiment according to the invention of the device with dielectric disks;

FIG. 8

- Sketch of an embodiment of the invention device with radially radially extending from the anode to the cathode dielectric surface elements;

FIG. 9

- Sketch of a device according to the invention with a plurality of juxtaposed electrode assemblies;

FIG. 10

- Sketch of a device for fluid treatment with a rotatably arranged electrode assembly and a drive unit;

FIG. 11

- Sketch of a device for fluid treatment with several alternately acted upon by high voltage pulses anodes;

FIG. 12

- Sketch of a device for fluid treatment with multiple groups of anodes, which are alternately applied with high voltage pulses.

FIG. 1 shows a sketch of a lack of dielectric surface elements not inventive device 1 for the treatment of fluids, in the form of drinking water, process water or wastewater or other aqueous solutions. With this device 1 impurities such as bacteria, viruses, fungi or chemical residues can be made harmless. So the device 1 z. B. suitable to remove pharmaceutical residues. For this purpose, the device 1 has an electrode arrangement 2 which is formed from a cylindrical cathode 3 and an anode 4 which extends coaxially in the interior of the cathode 3 in a linear manner. The anode 4 may be, for example, a rod electrode or a wire electrode. Particularly suitable is an electrode made of tungsten or a tungsten alloy.

It can be seen that the fluid 5 to be treated is conducted in a fluid flow through the fluid volume 6, which is delimited by the cylindrical cathode 3 of the electrode arrangement 2. In this case, however, the cylindrical cathode 3 may also be a grid-like structure which adjoins a cylindrical, non-conductive wall, such as, for example, a glass vessel or a glass tube. The cathode 3 is electrically grounded. The anode 4 is connected to a high-voltage unit 7, which is set up to generate high-voltage pulses 8. For this purpose, for example, the use of a multistage Marx bank or staggered Blumlein generators is suitable.

When the anode 4 is acted upon by the high-voltage pulses 8, corona discharges are formed along the extension direction of the linear anode 4, which extend radially to the surrounding cathode 3. In this case, the voltage amplitude of the high-voltage pulses 8 is to be adapted to the radial distance between anode 4 and cathode 3 and the fluid to be treated, in particular with regard to the conductivity of the fluid, that voltage breakdowns be prevented as possible.

The anode 4 is then acted upon by the high-voltage unit 7 with a series of high-voltage pulses 8, which have a pulse duration in the range of 50 to 400 nanoseconds (FWHM). The pulse rise times of the high voltage pulses 8 are adjusted by suitable means of the high voltage unit 7 so that they are in the range of 1 to 40 nanoseconds. Thus, the rising edge of the high voltage pulses 8 is very steep, which leads to a significantly improved efficiency of the fluid treatment. The very short and steep pulses ensure that the energy is transferred very quickly to the surrounding electrons of the fluid 5. This leads to a plasma which optimally converts the electrical energy required for the treatment of the fluid 5 Reaktionsschemie without a significant proportion of the energy in heating processes of the plasma and the fluid 5 is wasted. By the very steep and fast high voltage pulses 8, the intensity of the shock waves resulting from the plasma can be increased, which improves the efficiency of the fluid treatment.

FIG. 2 allows a diagram of a high voltage pulse 8 to be detected. It becomes clear that the high-voltage pulse has a pulse duration of about 250 nanoseconds (FWHM). The pulse duration is thus defined by the half-width of the voltage amplitude of the high-voltage pulse (fill width at half maximum = FWHM). The beginning and the end of the pulse duration are defined by half of the maximum voltage amplitude. In the present example, the maximum voltage amplitude is 80 kilovolts. The pulse duration is thus defined by the time between the passage of the voltage amplitude by the half voltage maximum, ie at 40 kilovolts.

It can be seen that the high-voltage pulse has a very short rise time of approximately 30 nanoseconds in relation to the pulse duration. The pulse rise time is determined from the beginning of the high voltage pulse until the time t = 0 at half the voltage maximum and reaching the maximum voltage.

When the anode 4 is acted upon by the high-voltage pulse 8, a current pulse 9, which has a visibly damped oscillation with a peak current of 500 amperes (0.5 kA) and a pulse duration of approximately 100 nanoseconds, arises on the line to the anode 4. This short, sharp and damped current pulse 9 is the result of the short voltage pulse 8 with a very steep rising edge.

With the help of the application of the anode 4 with such high-voltage pulses 8 corona discharges in the fluid volume 6 are caused. This hydroxyl radicals are generated, which consist of a hydrogen and an oxygen atom and have a relatively large redox potential in the range +2.8 volts. Such hydroxyl radicals are, in addition to fluorine, one of the strongest oxidizing agents and also suitable for splitting up those stable components which can not be adequately treated by conventional oxidizing agents, such as chlorine or ozone. The hydroxyl radicals generated by the corona discharges by means of plasma processes have been found to be particularly suitable for reducing pharmaceutical residues in the water. The generation of corona discharges directly in the fluid leads to high concentrations of hydroxyl radicals which are formed directly in the fluid volume 6 to be treated. Such hydroxyl radicals have a very short life of less than a millisecond in the fluid, so efficient spreading throughout the fluid volume 6 is critical to the effectiveness of the fluid treatment.

In addition to the generated by the corona discharges hydroxyl radicals and the strong pulsed electric fields in the fluid volume 6 for efficient inactivation of microorganisms in the fluid 5. In addition, ultraviolet light is imitated by the filaments of corona discharges, resulting in further microbiological Inactivation leads. In addition, due to the short pulse rise times at the short pulse durations, very strong shock waves occur in the vicinity of the filaments of the corona discharges, which destroy cell structures efficiently.

In the simplest embodiment of the device 1, the anode 4 is arranged coaxially in the fluid volume 6 to the cylindrical cathode 3 as a wire or rod electrode. The cylindrical cathode 3 may be e.g. a section of a metal tube that serves as a ground electrode and is grounded. In this way, existing piping or pumping systems can be used and modified by installing an anode 4 and connecting a high voltage unit 7. It is then only an insulated feedthrough 8 for the supply line 11 between the high voltage unit 7 and anode 4 is required, with which the anode 4 is supplied with the high voltage pulses 8.

The anode 4 is heavily stressed when subjected to high-voltage pulses and, in particular in the case of a wire electrode, can optionally be continuously fed by a conveyor unit and thus replaced.

The diameter of the cylindrical cathode 3 depends on the operating conditions and may preferably be in the range of 1 to 50 cm in diameter and preferably in the range of 5 to 10 cm in diameter. In order to treat larger volumes of fluid or fluid flows modular devices 1 are conceivable in which a plurality of such electrode assemblies are connected in parallel with such relatively narrow pipe systems.

The high voltage electrode, that is, the anode 4 is connected to the high voltage unit 7 via the supply line 11, which generates the high voltage pulses 8 and thus the high voltage electrode 4 is applied. In this case, the diameter of the cathode or the distance between the anode 4 and the cathode 3 to the conductivity of the fluid to be treated 5 and the selected maximum Adjust voltage amplitude of the high voltage pulses 8 and the pulse duration so that breakdowns are prevented as safe as possible.

For efficient fluid treatment, the voltage amplitude of the high voltage pulses 8 should be more than 5 kilovolts. For a tube diameter of the cathode 3 in the range of 5 to 10 cm in diameter, the voltage amplitude of the high-voltage pulses 8 should preferably be selected in the range of 50 to 150 kilovolts. This makes it possible to achieve a very efficient fluid treatment while avoiding breakdowns.

FIG. 3 shows a sketch of the non-inventive device 1 due to the lack of dielectric surface elements FIG. 1 with outlined corona discharges 12 in the fluid volume 6. The anode 4 is thereby acted upon by high-voltage pulses 8. It can be seen that the corona discharges 12 extend over the length of the anode 4 in the direction of extent from the anode 4 radially outward to the surrounding cathode 3. The spread of these corona discharges 12 depends in addition to the voltage amplitude substantially on the duration of the high voltage pulses. The pulse duration is to be chosen so short that the energy of the high voltage pulses is efficiently converted into a reaction chemistry and is not unnecessarily consumed by heating plasma and the fluid 5. This is achieved by very short pulse durations in the range of 50 to 400 nanoseconds (FWHM).

The pulse rise time of the high voltage pulses 8 has proven to be an essential criterion. The pulse rise time is directly related to the electrode chemistry caused by the corona discharges 12, which in turn correlates with the rate of hydroxyl radical generation and the intensity of other plasma processes that can be used to inactivate microorganisms. The decisive factor here is that the pulse rise time in relation to the pulse duration is very short. The pulse rise times with pulse durations of 50 to 400 nanoseconds should be in the range of 1 to 40 nanoseconds.

The resulting current pulses should be in the range of 1 to 100 nanoseconds pulse duration. Such short current pulses are advantageous for generating efficient corona discharges. The current pulses are determined by the voltage pulse. A fast sequence of current pulses can be achieved with short and strong damped current pulses, as they are z. B. can be generated using a multi-level Marx Bank, achieve good.

The pulse repetition rates should be chosen so that the corona discharges have largely subsided before a new corona discharge in the area in question is caused.

With this device and the corresponding method for fluid treatment, in particular pharmaceutical residues can be significantly reduced. After loading a fluid volume with about 6000 pulses at a pulse repetition rate of 20 Hertz, the content of investigated pharmaceutical residues could already be approximately halved. After about 80,000 discharges, far more than 80% of pharmaceutical residues can usually be removed. The method has been found to be suitable for treating pharmaceutical residues, e.g. Carbamazepines, diatrizoates, diazepam, diclofenac, ethinylestradiol, ibuprofen and trimethropine are largely removed from wastewater.

This fluid treatment also ensures that harmful concentrations of nitrates and nitrites are largely prevented. A post-treatment of the fluid 5 to reduce the increased by the fluid treatment with conventional processes nitrate and nitrite content is therefore not required.

To increase the efficiency of the fluid treatment are modifications to the Basic structure of the illustrated device conceivable. So z. B. several anodes 4, for example, by means of parallel rods or wires simultaneously or preferably alternately one behind the other with high voltage pulses 8 are applied. These multiple anodes 4 are arranged in the fluid volume 6 relative to a common cathode 3.

FIG. 4 allows a device 1 not according to the invention to be recognized due to the lack of dielectric surface elements, in which the wire-shaped or rod-shaped anode 4 is surrounded by a non-conductive tube 13. The tube 13 has openings 14 which are distributed over the length and circumference of the tube 13. The tube 13 has a gas inlet 15 for introducing a reaction gas G such as oxygen. The corona discharges 12 generated by the action of the anode 4 with high-voltage pulses 8 thereby break up the gas molecules into effective radicals, such as, for example, into atomic oxygen. The corona discharges 12 extend from the anode 4, starting through the openings 14 into the fluid volume 6. The filaments of the corona discharges interact with both the introduced reaction gas G and the surrounding fluid 5.

FIG. 5 lets a sketch of a lack of dielectric surface elements not inventive device 1 for fluid treatment recognize. Here, the wire or rod-shaped anode 4 is in turn surrounded by a surrounding electrically non-conductive tube. The tube 16 in turn has openings 17, through which corona discharges when applying the anode 4 with high voltage pulses 8 pass through. With the aid of such a perforated tube 16 surrounding the anode 4, the filaments of the corona discharges 12 exit through the openings 17 and then extend along the surface of the perforated tube 16. Thus, the acted upon by the corona discharges 12 fluid volume 6 is very effectively increased. The filaments that extend along the dielectric have a different energy distribution than the filaments extending directly in the fluid 5, resulting in a much higher generation rate of radicals compared with the simple in FIG. 3 shown generation of corona discharges 12 directly in the fluid 5 leads.

Unlike a pure coating of the anode 4 with a porous material, the surrounding perforated tube 16 with dedicated openings 17 effects an improved distribution of the filaments of the corona discharges 12 with an even more efficient energy distribution. This may be due to the fact that the filaments of the corona discharges 12 can pass undisturbed through the openings 17 from the anode 4, while they first have to search for a suitable path in the case of a porous coating.

The with the according FIG. 5 Modified device 1 caused physical mechanisms at the interface to the dielectric tube 16 have been found to be particularly effective for the degradation of chemicals such as pharmaceuticals.

FIG. 6 lets a device 1 recognize. in which in the fluid volume 6 filling elements 18 are introduced, for example in the form of balls, between which interstices are present. The filaments of the corona discharges 12 which are formed when high-frequency pulses 8 are applied to the anode 4 can extend through the intermediate space between the filling elements 18. This ensures very efficient reaction paths along the filling elements 18.

The filling elements 18 are nonconductive, ie dielectric, and have either catalytic or absorbing properties. As catalytic filling elements 18 are preferably materials such as titanium dioxide. Silica dioxide or aluminum-containing filling elements 18 are particularly suitable as absorbents. With the aid of such absorbent or catalytic filling elements 18 synergies along the surfaces can be used to increase the efficiency of the decontamination of the fluid 5.

FIG. 7 lets recognize an embodiment of the device 1 according to the invention. In this case, a plurality of dielectric disks 19 are arranged in the extension direction of the anode 4, which extend radially from the anode 4 to the cylindrical cathode 3. With the aid of these dielectric disks 19, it is possible for the filaments of the corona discharges 12 to propagate transversely to the flow direction of the fluid 5 along the surface of the dielectric disks 19. The fluid flowing across the surface of the discs 19 is thus very effectively treated by the physical and chemical effects produced by the corona discharges 12. In the dielectric disks 19 there are passage openings 20 through which the fluid 5 can flow.

FIG. 8 shows another embodiment according to the invention of the device 1 for fluid treatment. In this case, in turn extends a wire or rod-shaped anode 4 coaxial with a cylindrical cathode 3 in the partial section of the illustrated cathode 3 therethrough. From this anode protrude at a distance from the anode 4 arranged dielectric surface elements 21. These dielectric sheet members 21 span a plane in the extending direction of the anode and radially in a portion between the anode 4 and the surrounding cathode 3. The corona discharges 12 generated when high voltage pulses are applied to the anode 4 are then propagated with their filaments on the surface of the surface elements 21 starting from the anode 4 in the direction of the cathode 13 radially and in the direction of extension of the anode 4. Thus, the effective surface used for the fluid treatment is substantially increased without affecting the flow conditions for the fluid. It is clear that the surface elements 21 are arranged in a star shape distributed over the circumference of the anode 4. They can be as rectangular in cross section plates or as shown as elements with be configured circular segment-shaped cross-section.

FIG. 9 1 shows a sketch of a device 1 according to the invention for fluid treatment, in which a plurality of electrode arrangements 2 are arranged parallel to one another. Thus, the entire fluid volume 6 or the fluid flow rate can be ensured while ensuring an efficient geometry of the electrode assemblies 2. In the illustrated embodiment, radially extending dielectric surface elements 21 are present within the electrode assembly 2. In a corresponding manner could also electrode assemblies 3 with disc-like surface elements 19 or with filling elements 18 in the fluid volume 6 according to the embodiment of FIG. 6 be provided.

FIG. 10 makes another device 1 not according to the invention detectable due to the lack of dielectric surface elements. Here, the rod-shaped anode 4 of the electrode assembly 2 is arranged rotatable about a rotation axis. At the anode 4 mitrotierende dielectric surface elements are arranged. The anode 4 is, as arranged by the rotary arrow, rotatable and is driven by a drive unit 23. The rotational frequency is preferably in the range of the pulse repetition rate with a tolerance of <±> 10%. This ensures that when the anode 4 is re-pressurized with a high-voltage pulse 8 in the regions of the new corona filaments, the plasma has largely decayed and does not impair the efficient conversion of energy into reaction processes.

FIG. 11 lets recognize a device 1 not according to the invention for fluid treatment due to the lack of dielectric surface elements. Again, an electrode assembly 2 is provided which is formed of a cylindrical cathode 3 and a plurality of anodes 4. The plurality of anodes 4 are arranged distributed in the fluid volume 6 within the space enclosed by the cathode 3 and each with a supply line 11 with the High voltage unit 7 connected. In this embodiment, the high-voltage unit 7 is set up such that the individual anodes 4 or groups of anodes 4 are alternately acted upon in each case by high-voltage pulses 8. This is indicated by the high-voltage pulses 8 shown offset in time (temporally) adjacent to the supply line 11.

In the illustrated device 1 two spaced apart anodes 4 are acted upon simultaneously with a high voltage pulse 8. The two groups of anodes 4 are offset so that in a decay process after acting on a group of anodes 4 with a high voltage pulse 8, the at least one further group of anodes 4 can already be acted upon by a high voltage pulse 8 without the corona discharges generated thereby the decay process are affected. The respectively simultaneously acted upon anodes 4 of a group are thus arranged spatially offset to a temporally before or after acted upon group of anodes 4. Starting from the anodes 4, a number of dielectric surface elements extend radially in the direction of the associated cylindrical cathode 3.

FIG. 12 leaves a device 1 not according to the invention due to the lack of dielectric surface elements FIG. 11 recognize. Again, a plurality of spatially spaced apart in the interior of the cathode 3 arranged anodes 4 are provided. In this embodiment, z. B. two anodes 4 connected together to form a group and connected to a common feed line 11 to the high voltage unit 7. In this case, the two anode groups are applied alternately by the time-shifted high-voltage pulses 8. Starting from the anodes 4, a number of dielectric surface elements extend radially in the direction of the associated cylindrical cathode 3.

In all the embodiments described above, the cathode 3 may be a closed, the fluid volume to the outside limiting cylinder or on the outer circumference by a closed container (eg a glass cylinder) limited cylindrical grid. A "pipe" is thus understood as meaning a through-breaking grid pipe. Other geometries, such as plate-shaped electrodes are conceivable.

Claims (6)

1. An apparatus (1) for treating fluids (5) in the form of drinking water, service water, waste water or aqueous solutions by producing corona discharges in a fluid volume (6), wherein the apparatus has an electrode assembly (2) with at least one cylindrical cathode (3) and at least one linear anode (4) arranged in the interior of the cathode (3) and at a distance from the cathode (3), and a high voltage unit (7) to produce high-voltage pulses (8), wherein the high-voltage unit (7) is connected to the electrode assembly (2) in order to apply high-voltage pulses (8) to the at least one anode (4), and wherein the electrode assembly (2) is configured to accommodate the fluid (5) to be treated in the space between the at least one cathode (3) and the at least one anode (4), wherein the high-voltage unit (7) is configured to produce high-voltage pulses (8) with pulse rise times within a range of 1 to 40 nanoseconds and a pulse duration within a range of 50 to 400 nanoseconds, characterized in that a plurality of dielectric surface elements (19, 21) extend radially toward the associated cylindrical cathode (3) starting from the at least one linear anode (4).
2. The apparatus (1) according to claim 1, characterized in that the high-voltage unit (7) is configured to generate the high-voltage pulses (8) with a pulse repetition rate within a range of 10 to 1000 Hertz.
3. The apparatus (1) according to claim 2, characterized in that the high-voltage unit (7) is configured to generate the high-voltage pulses (8) with a pulse repetition rate within a range of 50 to 150 Hertz.
4. The apparatus (1) according to one of claims 1 to 3, characterized in that the high-voltage unit (7) is configured to generate the high-voltage pulses (8) with a voltage amplitude of more than 5 kilovolts.
5. The apparatus (1) according to claim 4, characterized in that the high-voltage unit (7) is configured to generate the high-voltage pulses (8) with a voltage amplitude within a range of 50 to 200 kilovolts, and preferably within a range of 50 to 150 kilovolts.
6. The apparatus (1) according to one of claims 1 to 5, characterized in that a plurality of dielectric discs (19) are arranged sequentially in the direction of the longitudinal extension of a common anode (4), wherein the anode (4) extends through the dielectric discs (19), the dielectric discs (19) extend radially toward the associated cathode (3), and wherein the dielectric discs (19) have passages (20) for conducting the fluid (5) to be treated.

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